Execute Operation - GE Multilin 745 Communications Manual

CHAPTER 2: MODBUS PROTOCOL

Execute operation

745 TRANSFORMER PROTECTION SYSTEM – COMMUNICATIONS GUIDE
Message format and example:
Request to read 3 register values starting from address 0200 from slave device 11.
Master query message
Slave address
Function code
Data starting address
Number of registers (high, low)
CRC (low, high)
Slave response
Slave address
Function code
Byte count
Data #1 (high, low)
Data #2 (high, low)
Data #3 (high, low)
CRC (low, high)
Modbus implementation: Force single coil
GE Multilin implementation: Execute operation
This function allows the master to perform various operations in the 745. The two-byte
value of FF00h must be sent after the operation code for the operation to be performed.
Message format and example:
Request to perform reset operation in slave device 11.
Master query message
Slave address
Function code
Operation code (high, low)
Code value (high, low)
CRC (low, high)
Slave response
Slave address
Function code
Operation code (high, low)
Code value (high, low)
CRC (low, high)
Example Description
11 query message for slave 11
03 read register values
02 00 data starting at address 0200
00 03 3 register values = 6 bytes total
06 E3 computed cyclic redundancy check
Example Description
11 response message from slave 11
03 read register values
06 3 register values = 6 bytes total
02 2B register value in address 0200 = 022B
00 00 register value in address 0201 = 0000
00 64 register value in address 0202 = 0064
C8 BA computed CRC code
Example Description
11 query message for slave 11
05 execute operation
00 01 remote reset
FF 00 perform operation
DF 6A computed cyclic redundancy check
Example Description
11 response message from slave 11
05 execute operation
00 01 remote reset
FF 00 perform operation
DF 6A computed cyclic redundancy check
MODBUS PROTOCOL
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